The spirochete Borrelia hermsii avoids the immune response of its mammalian host through multiphasic antigenic variation. Serotype specificity is determined by Variable major proteins (Vmp), in the outer membrane. Through a non reciprocal recombination between linear plasmids, a formerly silent vmp gene replaces another vmp gene at a telomeric expression locus downstream from a common expression site. B. hermsii before and after the switch from serotype 7 to serotype 21, was examined in detail. The nucleotide sequence of the vmp7 and vmp21 genes and flanking regions was determined. The vmp7 and vmp21 are 77% identical in their coding sequence, and the deduced translation products are 63% identical. No antigenic cross reactivity is observed between Vmp7 and Vmp21. This suggests a folding of the proteins in which the similar regions are buried, and not exposed when it is presented at the bacterial surface. Vmp7 and Vmp21 have consensus sequences of prokaryotic lipoproteins and are processed as such when expressed in E. coli. The 5' regions of silent and expressed vmp7 and vmp21 were compared. Silent and active vmp7 and vmp21 genes shared a block of homologous sequence at their 5' ends. Sequences upstream of silent vmp7 and vmp21 genes lacked a promoter and differed substantially from each other. In this antigenic switch a vmp gene was activated by a recombination event which placed it downstream of a promoter. The vmp gene promoter is preceded by a poly(dT dA) ran and three imperfectlyrepeated elements of 2 kb. Each of the 2 kb repeats contains inverted repeats of approximately 0.2 kb at their termini. There is no evidence of the presence of similar elements elsewhere in the genome of B. hermsii. One or more of these elements may stimulate vmp gene switch or expression. The African relapsing fever species Borrelia crocidurae and the American species B. hermsii display many similarities. In both species the vmp genes are localised to linear plasmids, and the vmp genes are activated on the transcriptional level. The nucleotide sequence of their expression sites, however, are not related. Still, the possibility that the switch is mechanistically similar in B. crocidurae and B. hermsii, cannot be ruled out. The binding of B. crocidurae causes aggregation of erythrocytes around the spirochete. The aggregation is reminiscent of the erythrocyte rosetting seen in malarial infections. The erythrocytes at the B. crocidurae surface may protect them from clearance by the host. Thus, the rosetting may constitute an additional mechanism in B. crocidurae for the evasion of the immune reaction. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1994, härtill 5 uppsatser.</p> / digitalisering@umu

The problem of inadequate measurement techniques for quantifying the isothermal solidification process during transient liquid phase sintering (TLPS) in binary isomorphous systems such as Ni-Cu, and the resulting uncertainty regarding the solidification mechanism and its sensitivity to important process parameters, has been investigated. A unique combination of differential scanning calorimetry (DSC), neutron diffraction (ND), and metallographic techniques has enabled the quantitative characterization of important TLPS stages (i.e., solid-state sintering, melting and dissolution, isothermal solidification, and homogenization) as well as verifying the re-melt behaviour of post-sintered specimens and measuring variable melting point (VMP) properties. This has resulted in the advancement of the fundamental understanding of liquid formation and its removal mechanism during isothermal, or diffusional, solidification. The Ni-Cu system was chosen for experimentation due to its commercial relevance as a braze filler material and also because it is an ideal model system (due to its isomorphous character) that is not well understood on a quantitative or phenomenological basis. Samples consisted of elemental Ni and Cu powder mixtures of varying particle size and composition. In DSC experiments, the progress of isothermal solidification was determined by measuring the enthalpy of melting and solidification after isothermal hold periods of varying length and comparing these to the measured enthalpy of pure Cu. The low melting enthalpies measured for all Ni/Cu mixtures heated just past the Cu melting point (1090°C) indicate that solid-state sintering and interdiffusion during heat-up significantly suppress initial liquid formation and densification from the wetting liquid. For samples heated well past the Cu melting point (1140°C), Ni dissolution causes increased initial liquid fractions and densification. It was found that significantly more time was required for complete liquid removal at 1140°C vs. 1090°C. This is attributed to the observed increase in initial liquid fractions formed at higher processing temperatures due to the dissolution of Ni. This effectively counteracts the increased diffusivities at these temperatures, and thus more time is required to completely remove the increased liquid content. TLP mixtures sintered at 1140°C using three different particle sizes revealed that fine base metal Ni particles cause high degrees of solid-state interdiffusion during heat-up, small initial liquid fractions, and accelerated liquid removal rates due to high surface area/volume ratios. A diffusion-based analytical model was developed to account for these effects (i.e., particle size, temperature, solid-state sintering, and dissolution). Comparison with experimental DSC results reveals that this model can accurately predict liquid removal given accurate diffusivities. Metallographic analysis of post-sintered DSC specimens via SEM and EDS indicates that isothermal liquid solidification leaves behind Ni-rich cores surrounded by Cu-rich matrix regions having compositions given by the Ni-Cu phase diagram solidus (CS) at a selected isothermal processing temperature (TP). ND experiments were used to investigate the melting event and interdiffusion during the isothermal hold segment by analyzing the evolution of the {200} FCC peaks of Ni and Cu. ND patterns were collected in situ at 1 minute intervals during prolonged sintering cycles for larger powder specimens. The Cu melting event was characterized by an abrupt decrease in Cu peak intensity at 1085°C as well as a shift towards higher 2 angles corresponding to lower Cu contents. This shifted residual peak (hereafter referred to as the CS peak) originates from regions of the specimen having compositions near solidus at TP. Immediately following the melting event, the evolution of ND patterns shows that these CS peaks grow rapidly, indicating the isothermal growth of a Cu-rich phase. These in situ findings confirmed the metallographic and DSC data and indicated that isothermal solidification of the liquid phase proceeds via the growth of a solute-rich solid solution layer surrounding the Ni particles. This occurs by the transient progression of the solid/liquid interface at compositions given by the liquidus and solidus (CS/CL). During sintering, diffraction intensities gradually increased at intermediate 2 angles between previous Ni and Cu peaks. ND patterns gradually evolved from initially having a broad double-peak profile to a sharper single-peak profile due to increased Ni-Cu interdiffusion. The 2position and width of the post-sintered peaks indicated very homogeneous sintered alloys. Metallographic analysis of post-sintered specimens having undergone prolonged sintering and homogenization revealed extensive Kirkendall pore formation from unequal diffusivities (DCu > DNi). In this study, the unique combination of diffusion-based modelling as well as DSC, ND, and supporting metallographic analysis has enabled the identification of characteristic sintering behaviour, important process parameters, and processing windows for TLPS in Ni-Cu systems. Quantitative and in situ information of this nature is absent in the previous TLPS literature.

The problem of inadequate measurement techniques for quantifying the isothermal solidification process during transient liquid phase sintering (TLPS) in binary isomorphous systems such as Ni-Cu, and the resulting uncertainty regarding the solidification mechanism and its sensitivity to important process parameters, has been investigated. A unique combination of differential scanning calorimetry (DSC), neutron diffraction (ND), and metallographic techniques has enabled the quantitative characterization of important TLPS stages (i.e., solid-state sintering, melting and dissolution, isothermal solidification, and homogenization) as well as verifying the re-melt behaviour of post-sintered specimens and measuring variable melting point (VMP) properties. This has resulted in the advancement of the fundamental understanding of liquid formation and its removal mechanism during isothermal, or diffusional, solidification. The Ni-Cu system was chosen for experimentation due to its commercial relevance as a braze filler material and also because it is an ideal model system (due to its isomorphous character) that is not well understood on a quantitative or phenomenological basis. Samples consisted of elemental Ni and Cu powder mixtures of varying particle size and composition. In DSC experiments, the progress of isothermal solidification was determined by measuring the enthalpy of melting and solidification after isothermal hold periods of varying length and comparing these to the measured enthalpy of pure Cu. The low melting enthalpies measured for all Ni/Cu mixtures heated just past the Cu melting point (1090°C) indicate that solid-state sintering and interdiffusion during heat-up significantly suppress initial liquid formation and densification from the wetting liquid. For samples heated well past the Cu melting point (1140°C), Ni dissolution causes increased initial liquid fractions and densification. It was found that significantly more time was required for complete liquid removal at 1140°C vs. 1090°C. This is attributed to the observed increase in initial liquid fractions formed at higher processing temperatures due to the dissolution of Ni. This effectively counteracts the increased diffusivities at these temperatures, and thus more time is required to completely remove the increased liquid content. TLP mixtures sintered at 1140°C using three different particle sizes revealed that fine base metal Ni particles cause high degrees of solid-state interdiffusion during heat-up, small initial liquid fractions, and accelerated liquid removal rates due to high surface area/volume ratios. A diffusion-based analytical model was developed to account for these effects (i.e., particle size, temperature, solid-state sintering, and dissolution). Comparison with experimental DSC results reveals that this model can accurately predict liquid removal given accurate diffusivities. Metallographic analysis of post-sintered DSC specimens via SEM and EDS indicates that isothermal liquid solidification leaves behind Ni-rich cores surrounded by Cu-rich matrix regions having compositions given by the Ni-Cu phase diagram solidus (CS) at a selected isothermal processing temperature (TP). ND experiments were used to investigate the melting event and interdiffusion during the isothermal hold segment by analyzing the evolution of the {200} FCC peaks of Ni and Cu. ND patterns were collected in situ at 1 minute intervals during prolonged sintering cycles for larger powder specimens. The Cu melting event was characterized by an abrupt decrease in Cu peak intensity at 1085°C as well as a shift towards higher 2 angles corresponding to lower Cu contents. This shifted residual peak (hereafter referred to as the CS peak) originates from regions of the specimen having compositions near solidus at TP. Immediately following the melting event, the evolution of ND patterns shows that these CS peaks grow rapidly, indicating the isothermal growth of a Cu-rich phase. These in situ findings confirmed the metallographic and DSC data and indicated that isothermal solidification of the liquid phase proceeds via the growth of a solute-rich solid solution layer surrounding the Ni particles. This occurs by the transient progression of the solid/liquid interface at compositions given by the liquidus and solidus (CS/CL). During sintering, diffraction intensities gradually increased at intermediate 2 angles between previous Ni and Cu peaks. ND patterns gradually evolved from initially having a broad double-peak profile to a sharper single-peak profile due to increased Ni-Cu interdiffusion. The 2position and width of the post-sintered peaks indicated very homogeneous sintered alloys. Metallographic analysis of post-sintered specimens having undergone prolonged sintering and homogenization revealed extensive Kirkendall pore formation from unequal diffusivities (DCu > DNi). In this study, the unique combination of diffusion-based modelling as well as DSC, ND, and supporting metallographic analysis has enabled the identification of characteristic sintering behaviour, important process parameters, and processing windows for TLPS in Ni-Cu systems. Quantitative and in situ information of this nature is absent in the previous TLPS literature.

[EN] ABSTRACT The traditional Taiwan polychrome include a wide range of materials, with very different behaviors showing problems of different nature that sometimes requires the application of appropriate adherence and/or consolidation treatment. From this, a study has been conducted aimed to identify these materials and their behaviors as well as, the proposal of a proper adhesive/consolidant with physico-chemical stability and low toxicity. The identification of the materials confirms the use of porcine blood as binder in the preparation layer and tung oil as the binder in the paint layer. Besides, the multi-technical approach by using FTIR, GC-MS and VMP allow the dating of the polychrome under study. The application of a proper treatment on paintings will depends on the adherent/consolidant properties that could appear during and/or post the treatment as: i) mechanical properties (strength, flexibility); ii) hydric (permeability to water vapor and other gases); iii) the physico-chemical stability one the adhesive/consolidant has been apply. Here we propose, the use of an andhesive/consolidant based on technical gelatin, in combination with the correct concentration of additives: glycerol as plasticizer and citronella as natural fungicide, for the conservation and restoration of the polychrome decoration present on different places in the architectural complex of the Longshan Temple in Lukang, Taiwan belonging to the XVIII century. In a second step the study of the chemical and morphological changes demonstrate that the use of glicerol and citronella as additives improves the physic-mechanical properties and slows the ageing process of the adhesive/consolidant. Moreover, the citronella oil inhibits proliferation of fungi Aspergillus niger (CECT-2088), Chaetomium globosum (CECT-2701), Fusarium oxysporum (CECT-2154), Mucor rouxii (CECT-2655), Penicillium chrysogenum (CECT-2655) y Trichoderma pseudokoningii. (CECT-2937). / [ES] RESUMEN Los materiales que componen la policromía tradicional en Taiwán, son muy diversos y además presentan problemas de diferente naturaleza que requieren la aplicación de tratamientos de adhesión y consolidación adecuados para cada caso. El estudio llevado a cabo incluye la identificación de sangre porcina como el aglutinante en la capa de preparación y el aceite de tung como el aglutinante en la capa pictórica. Además, combinando las técnicas analíticas (FTIR, GC-MS y VMP) se ha logrado la datación de las policromías analizadas. Los tratamientos de intervención de obra pictórica dependen de múltiples factores, tales como las propiedades adherentes/consolidantes que se ponen de manifiesto durante el tratamiento y seguidamente, las propiedades mecánicas (resistencia mecánica, flexibilidad), hídricas (permeabilidad al vapor de agua y otros gases) y la estabilidad físico-química una vez el adhesivo/consolidante ha sido aplicado. A ellas hay que sumar otros aspectos tales como toxicidad, impacto medioambiental, coste económico y disponibilidad. El presente estudio, propone un adhesivo/consolidante obtenido de la gelatina técnica, y se adiciona unos aditivos, el glicerol (plastificante) y la citronela (fungicida natural), para la conservación y restauración de la decoración polícroma aplicada en diferentes partes del complejo arquitectónico del Templo Longshan en Lukang (siglo XVIII, Taiwán). Finalmente, se ha demostrado que la adicción de glicerol y aceite de citronela mejora las propiedades físico-mecánicas y ralentizan el proceso de envejecimiento del adhesivo/consolidante. Además, el aceite de citronela inhibe la proliferación de los hongos Aspergillus niger (CECT-2088), Chaetomium globosum (CECT-2701), Fusarium oxysporum (CECT-2154), Mucor rouxii (CECT-2655), Penicillium chrysogenum (CECT-2655) y Trichoderma pseudokoningii. (CECT-2937). / [CAT] RESUM Els materials que componen la policromía tradicional a Taiwan, són molt diversos i a més presenten problemes de diferent naturalesa que requereixen l'aplicació de tractaments d'adhesió i consolidació adequats per a cada cas. L'estudi dut a terme inclou la identificació de sang porcina com l'aglutinant a la capa de preparació i l'oli de tung com l'aglutinant a la capa pictòrica. A més, combinant les tècniques analítiques (FTIR, GC-MS i VMP) s'ha aconseguit la datació de les policromies analitzades. Els tractaments d'intervenció d'obra pictòrica depenen de múltiples factors, tals com les propietats adherents / consolidants que es posen de manifest durant el tractament i seguidament, les propietats mecàniques (resistència mecànica, flexibilitat), hídriques (permeabilitat al vapor d'aigua i altres gasos ) i l'estabilitat fisicoquímica un cop l'adhesiu / consolidant ha estat aplicat. A tot aixo, cal sumar altres aspectes com ara toxicitat, impacte mediambiental, cost econòmic i disponibilitat. El present estudi, proposa un adhesiu / consolidant obtingut de la gelatina tècnica, i s'addiciona uns additius, el glicerol (plastificant) i la citronela (fungicida natural), per a la conservació i restauració de la decoració polícroma aplicada en diferents parts del complex arquitectònic del Temple Longshan a Lukang (segle XVIII, Taiwan). Finalment, s'ha demostrat que l'addicció de glicerol i oli de citronella millora les propietats físico-mecàniques i ralenteixen el procés d'envelliment de l'adhesiu / consolidant. A més, l'oli de citronella inhibeix la proliferació dels fongs Aspergillus niger (CECT-2088), Chaetomium globosum (CECT-2701), Fusarium oxysporum (CECT-2154), Mucor rouxii (CECT-2655), Penicillium chrysogenum (CECT-2655) i Trichoderma pseudokoningii. (CECT-2937). / Lee, Y. (2015). La técnica de la policromía en los artesonados de templos budistas en Taiwán: caracterización científica y estudio de la aplicabilidad de consolidantes biocompatibles para su conservación [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/59465 / TESIS

The aim of diploma thesis is translation, customization, realization and publication English version of Entry profile which is part of ISO/IEC 29110 in Eclipse Process Framework Composer tool with own methodology of realization so that profile will be available to Czech expert public. The goals are achieved by conversion of Entry Profile in Eclipse Process Framework Composer tool into web form. The first benefit of diploma thesis is description and characteristics of Entry Profile which is part of ISO/IEC 29110 standard, which serves to profile understanding and its practical usage. The second benefit is creation own methodology which allows Entry Profile conversion into electronic version. For profile realization is used Eclipse Process Framework Composer tool. The third benefit is detail reference book of profile realization in Eclipse Process Framework Composer. The main benefit is Entry Profile created in web form, which is available to expert public. At the beginning of diploma thesis is described Entry Profile, its goal, structure and implementation packages. In third chapter is described concept of Unified Method Architecture which serves as theoretical input for chapter about Eclipse Process Framework Composer tool. In fourth chapter is characterized tool for management and maintenance methodology - Eclipse Process Framework Composer. Follows chapter about methodology of profile realization in Eclipse Process Framework Composer. Sixth chapter is detail reference book realization of Entry Profile in Eclipse Process Framework Composer. In following chapter is profile published in web form. Eight chapter evaluates realization and publication in Eclipse Process Framework Composer tool.